MARIE SKŁODOWSKA-CURIE ACTIONS Innovative Training Networks (ITN) European Joint Doctorate (EJD)

Advanced Training Course ATC2 Nanomaterials for wastewater treatment

Application of ceramic membranes in wastewater treatment

Maja Zebić Avdičević, Ph.D.

Zagreb, 16th-18th September 2020 MEMBRANE SEPARATION PROCES History

1748 J. Abbe Nollet discovered the phenomenon of osmosis. J.A. Nollet, Lecons de physique experimentale, Hippolyte-Louis Guerin and Louis-Francios Delatour, Paris, 1748.

1833 GRAHAM studied the diffusion of gases through different media and discovered that rubber exhibits different permeability to different gases

1867 Traube prepared the first artificially membrane

1907 Bechold introduced term ultrafiltration forcing solutions at pressures up to several atmospheres through membranes prepared by impregnating filter paper with acetic acid collodion

1950 Hassler introduces the first concept of membrane desalination describing „salt repelling osmotic membranes and permselective films” Milestones in membrane development

Desalination by cellulose acetate films (Breton & Reid 1959)

Asymetric cellulose acetate membranes (Loeb & Sourirajan 1962)

First spiral-wound module (General Atomics 1963)

First hollow fibre module (DuPont 1967) Thin Film composite membrane developed (Cadotte1972) Nanofiltration widely available (Bfluid Systems, Nitto Denko, Film Tec 1986)

1960 1970 1980 1990 2000 2010

First commercial thin film composite (Riley @ Fluid Systems, 1975) First large solvent RO separation (grace Davison & Mobil Oil, Beaumont, TX 1998) Water Factory 21 built (OCWD 1975) Membranes are physical barriers which can efficiently remove MEMBRANE suspended solids, turbidity, colloidal matter, bacteria, algae, parasites, viruses, natural organic matter, additives from SEPARATION chemical water treatment and other substances from water

PROCESSES Membrane technology is considered first choice technology for water treatment.

Pore size is defined with the lowest value of molecular weight for the substance which can be removed by the membrane - molecular weight cut-off – MWCO expressed in Da

In term of driving force, membrane operations can be divided into:

. Pressure - microfiltration, ultrafiltration, nanofiltration, reverse osmosis

. Concentration - dialysis gradient, pervaporation, osmosis (forward osmosis)

. Electrode potential - electrodialysis, electrodeionization, electrofiltration

. Temperature - membrane distillation Air protection Water Energetics protection

Pharmacy Breeding

Membranes Application

Medicine Argiculture

Soil Food protection Selective Delivery Separation Discriminatory

Application Application

Industrial relevance Membrane competing with Membrane processes with No alternative to membrane conventional processes clear advantage processes State of art processes High Water desalination, (waste) Production of ultrapure water Arfificial kindey, fuel cell water treatment separators Medium Natural gas treatment air Downstream processes of Terapeutic devices for separation bioproducts controlled drug releace Low Dehydration of solvents Biosensors Diagnostic devices Emerging processes High Membrane reactors MBR Artificial liver Medium Organic/organic separators Effluent recycling Immune isolation of cells Low Organic vapour recovery Affinity membranes MEMBRANE SEPARATION PROCES vs CONVENTIONAL METHODS

Advantages Disadvantages • defined size of membrane material that allows • Price the removal of substances at the molecular-ion level • the tendency to block the pores of • achieving the desired water quality according membrane material that requires pre- to strictly prescribed standards treatment or often chemical cleaning of the • often less consumption of chemicals membrane • smaller space due to the high membrane • during separation, a certain amount of packaging capacity waste sludge is generated from the washing • easy to operate of the membrane that is needed to be • automatic process control and maintenance of adequately disposed equipment Membrane separation processes MEMBRANE SEPARATION PROCESSES

MF Suspended solids, MICROFILTRATION bacteria > 100 nm Macromolecules, UF viruses, bakteria, ULTRAFILTRATION colloids, proteins 2 nm

NF Salts NANOFILTRATION 1 nm RO Desalination, every REVERSE OSMOSIS substance except gases <1 nm MEMBRANE SEPARATION PROCESSES

MOLECULAR OPERATING MEMBRANE DRIVING PORE MECHANISM OF SEPARATION WEIGHT CUT OFF, PRESSURE, PROCESSES FORCE SIZE, NM KDA BAR

Pressure or Microfiltration Particle retention by size > 5 000 >100 < 2 vacuum

Ultrafiltration Pressure Particle retention by size 1 – 5 000 2-100 1-5

Nanofiltration Particle retention by size Pressure + membrane-solution interaction (dissolved 0.1 – 1 1-2 3-20 Reverse osmosis substance) + electrostatic interactions (lower pressures)

Particle retention by size Reverse osmosis Pressure + membrane-solution interaction (dissolved < 0.1 < 1 10-100 substance) + electrostatic interactions MEMBRANE SEPARATION PROCESSES Process parameters

The key parameters of each membrane process • Membrane resistance

• Driving force per unit membrane area

• Hydrodynamic conditions at the membrane- fluid boundary

• Blocking of pores and frequency of cleaning of the membrane MEMBRANE SEPARATION PROCESSES Process parameters

3 -2 -1 2 Flux (specific flow), JP [m m s ] represents the volume passing through the membranes per unit of surface A [m ] and the unit time t [s].

Flux is often expressed in units outside the SI system such as L m-2 h-1 or LMH. Flux is calculated based on the measured 3 -1 values of the flow permeation QP [m h ] and membrane surface according to:

J = P

𝑃𝑃 𝑄𝑄 Transmembrane Pressure, TMP [bar] is defined as the 𝐴𝐴difference between inlet and permeate pressure

= permeate = permeate 𝑝𝑝inlet+𝑝𝑝retentate 𝑇𝑇𝑇𝑇𝑇𝑇 2 − 𝑝𝑝 𝑇𝑇𝑇𝑇𝑇𝑇 𝑝𝑝inlet − 𝑝𝑝 The relationship between the applied pressure on the inlet to be separated and the permeate flux through the membrane can be described using Darcy's equation : = 𝑇𝑇𝑇𝑇𝑇𝑇 Where are μ liquid viscosity [Pa s; kg m-1 s-1] and𝐽𝐽𝑃𝑃 R [m-1𝜇𝜇] �total𝑅𝑅 resistance.

Total resistance is the resistance of the membrane to the passing of the liquid and the resistance caused by the irreversible and reversible blockage of the pores of the membrane. 3 -2 -1 -1 • Permeability of the membrane LP [dm m h bar ] represents the MEMBRANE flux component through the membrane per unit power drive difference. SEPARATION PROCESSES • For pressure membrane processes, fluid permeability through Process parameters membrane is the ratio of flux and transmembrane pressure

Transitional region = 퐽P 𝑃𝑃 Mass Transfer controlled 퐿 𝑇𝑇𝑇𝑇𝑃𝑃 Pressure region controlled J=const. = region )

J = 𝑇𝑇𝑇𝑇𝑃𝑃 ( 𝐽𝐽𝑃𝑃 휇 � 𝑅𝑅 Flux 𝐽𝐽 푘 � 𝑇𝑇𝑇𝑇𝑃𝑃 = ( ) Temperature ↑↓ Crossflow velocity ↑ 휇 푓 𝑇𝑇 Viscosity ↓ =

𝐽𝐽𝑇𝑇 � 휇𝑇𝑇 𝐽𝐽20°퐶 � 휇20°퐶 = Transmembrane pressure ( ) 휇𝑇𝑇 𝐽𝐽20°퐶 𝐽𝐽𝑇𝑇 � 𝑇𝑇𝑇𝑇𝑃𝑃 휇20°퐶 MEMBRANE SEPARATION PROCESSES Process parameters

Conversion or process utilization (Y) is the value of the percentage input of the input stream translated into the product (permeate)

3 -1 3 -1 Where Q [m h ] is flow rate of solution at input and QR [m h ] is retentate flow.

= 𝑄𝑄𝑃𝑃 𝑌𝑌 3 As the degree of conversion is higher, the specific consumption𝑄𝑄 of energy per m of permeate is smaller. Based on the mass balance for the substance C at the inlet:

= + = +

𝑄𝑄 𝑄𝑄𝑃𝑃 𝑄𝑄𝑅𝑅 𝑄𝑄 � 𝐶𝐶 𝑄𝑄𝑃𝑃 � 𝐶𝐶𝑃𝑃 𝑄𝑄𝑅𝑅 � 𝐶𝐶𝑅𝑅 -3 -3 -3 Where: C [g dm ] concentration of substance in input flow, CP [g dm ] concentration of substance in permeate and CR [g dm ] concentration of substance in retentate.

Retention or separation rate (R) is defined as the proportion of the substance from the inlet flow retained or separated by the membrane. The degree of separation can be expressed with respect to the desired parameter, such as turbidity, total suspended matter, total organic matter, etc.

= = 1 𝐶𝐶 − 𝐶𝐶𝑃𝑃 𝐶𝐶𝑃𝑃 𝑅𝑅 − 𝐶𝐶 𝐶𝐶

DEAD END Transmembrane pressure, TMP [bar]

= permeate

inlet INLET 𝑇𝑇𝑇𝑇𝑃𝑃 𝑝𝑝 − 𝑝𝑝 3 -2 -1 Permeate flux, JP [m m s ]

J = 푄P 𝑃𝑃 퐴 Conversion [%]

Y = P 𝑄𝑄 Separation efficiency [%] 𝑄𝑄

MEMBRANE R = P = 1 𝐶𝐶 − 𝐶𝐶 𝐶𝐶𝑃𝑃 − 𝐶𝐶 𝐶𝐶 PERMEATE

MEMBRANE SEPARATION PROCESSES Process parameters MEMBRANE SEPARATION PROCESSES Process parameters MEMBRANE SEPARATION PROCESSES Process parameters MEMBRANES Types and membrane selection MEMBRANES Types and membrane selection

Material Advantages Disadvantages Low Thermal Resistance (<30 ° C) Low Chemical Resistance (pH 3-6) Low price Low mechanical stability Cellulose acetate (CA) Simple production Biodegradable Limited chlorine resistance Good thermal (50 ° C) and chemical stability Polyamide (PA) Interval pH 3-11 Sensitive to chlorine Greater permeability compared to PA Less chemical resistant than PTFE Thermal resistance Polypropylene (PP) Sensitive to chlorine Good thermal (<75 ° C) and chemical stability Interval pH 1-13 Low resistance to aromatic hydrocarbons, ketones, ethers and Polysulfone (PS) Simple production esters Good chemical resistance to aliphatic hydrocarbons, halogenated Suitable for lower pressures hydrocarbons, alcohols and acids hydrophobic Excellent resistance to organic matter Only MF membranes are available Polytetrafluoroethylene (PTFE) High chemical stability to strong acids, bases and solvents High price Thermal stability (-100-260 ° C) Less chemical resistant than PTFE High resistance to solvents Polyvinylidene fluoride (PVF) Only MF and UF membranes are available Titanium oxide Good thermal resistance High price Fragile Good chemical and thermal resistance Zirconium oxide Available for MF and UF MEMBRANES Types and membrane selection

• According to morphology

• Anisotropic on the surface they have a thin active layer of material of smaller pore sizes which is attached to the supporting layer of higher porosity. Anisotropic membranes can be made from the same material (asymmetric) or composed of various components (composite).

• Isotropic Membrane Panel MEMBRANES Spacer Types and membrane Membrane sheet selection

Microstructure • membrane geometry: flat and cylindrical

• flat sheets - spiral or plate and frame

• flat membranes and support frames connected in series. The input stream is transmitted between modules 10 mm apart • submerged treatment system MEMBRANES

Types and membrane selection Cylindrical: Hollow fiber

• consists of several hundred long thin fibers of the large selective surface wound around the carrier of a pore diameter 50-3 000 μm

• less space than the flat membranes

• low value of the flux of the permeate • the modules are immersed in water and the permeate is collected inside the fiber - low direction inside-out • very small fiber diameters and their high packaging density and low operating pressures result in a longer lifetime MEMBRANES Types and membrane selection

• Cylindrical

• Tubular • arranged within a wider tube with diameter around 25 mm • water is fed through the tubes, and the permeate is collected from the outside of the tube (within the wider carrier tube) Permeate • permeate flows inside-out and the Feed retentate passes through the inside stream of the tube Retentate Feed stream • not suitable for treating water with high suspended solids Retentate

Permeate MEMBRANE MODULES PORE BLOCKING membrane fouling

Pore blocking due to organic, inorganic and colloidal substances accumulation on the membrane surface

PORE Intensity of pore blocking can be affected by hydrodynamic and BLOCKING operational terms and also by appropriate membrane selection

Effects: decrease of membrane performance, permeate flux reduction, increase of costs of operation, more frequent chemical cleaning, and finally, system failure

Intensive blocking causes increased flow resistance → increase of TMP → higher energy consumption and operational costs PORE BLOCKING

• the relationship between TMP and permeate flux can be described by resistance in series mode. • membrane resistance increases due blockage of the membrane pore due to: • Increases in concentrations of substances or ions (RO) close to the surface of the membrane • Placing heavily soluble substances on the surface of the membrane and forming a gel layer • Accumulation of retained suspended and solids on membrane surface and formation of cake layer

• resistances can be determined experimentally based on the measurement of the change of the permeate flux in time = + + = +

• the membrane resistance is determined based on the value -1 Rm [m𝑇𝑇 ] membrane푚 resistance,푟푒푣 푖푟푒푣 푚 푓 of the intrinsic permittivity of the new membrane The dust 𝑅𝑅 -1 𝑅𝑅 𝑅𝑅 𝑅𝑅 𝑅𝑅 𝑅𝑅 block can be temporarily or permanently irreversible and it Rrev [m ] hydraulic reversible resistance -1 can be removed only with the application of chemicals Rirev [m ] resistance hydraulic irreversible resistance. -1 Rf [m ] (total fouling resistance) sum of reversible and irreversible resistance is the total resistance due to pore blockage Methods for reduction of membrane fouling effect

• flux values PORE BLOCKING • tangential flow rates of inlet water • time of separation cycle duration • physicochemical cleansing procedure • cake filtration

COMPLETE BLOCKING STANDARD BLOCKING INTERMIDIATE BLOCKING CAKE FILTRATION MEMBRANE • Physical CLEANING • mechanical (rigid particle addition), • hydraulic (air and permeate in the direction of flow) • ultrasonic procedures

• permeate washing: • forward flush (FF) • Physical • backwash (BW) • Chemical • Physiochemical MEMBRANE CLEANING Chemical

Use of chemical agents and their cleaning efficiency is based on the transfer and penetration of the chemical to the precipitated or adsorbed membrane material where its dissolution or desorption occurs.

Chemical wash is carried out when flushing is not enough for flux recovery

Frequent chemical washing damages the membrane, therefore the application of chemicals should be carried out in a targeted manner and with regard to water properties

Efficiency of chemical cleaning depends on numerous factors such as: concentration of chemicals, pH, temperature and time of cleaning

. acids: hydrochloric, sulfuric, nitric, citric, oxalic, etc. . base: Sodium Hydroxide . celates EDTA . enzymes: . surfactants . biocides . oxidants MEMBRANE CLEANING Physiochemical

Chemically enhanced backwashing (CEB) cleaning is achieved by the action of the chemical and hydraulic effect of the filtrate, and numerous other processes such as chemical washings assisted by ultrasonic

It is carried out in three steps:

1. backwash with permeate 2. soaking in the appropriate chemical 3. backwash with permeate to remove the retained matter from the membrane surface

Cleaning In Place (CIP) - using hydrodynamic conditions (recirculation of cleaning solution, more effective than the CEB)

Factors affecting the effectiveness of cleaning are: type of chemical and its concentration, temperature, duration of cleaning and hydrodynamic conditions MEMBRANE CHARACTERIZATON

Methods associated with permeability and degree of retention: • Gas / Liquid Porometry (Bubble Point Method); liquid / liquid porometry; mercury porosimetry; permporometry; measuring gas or liquid fluxes; determination of the degree of retention of the dissolved substance Methods related to membrane surface morphology: • Microscopic techniques: scanning electron microscope (SEM); Field Emission Scanning Electron Microscope (FESEM); transmitting electron microscope (TEM); high resolution transmission electron microscopy (HRTEM); atomic force microscope (AFM); Scanning tunneling microscope (STM) Other techniques • gas adsorption / desorption; termoporometry; ultrasonic time-domain reflectometry (UTDR); light transmission; spectroscopic ellipsometry; nuclear magnetic resonance; electrokinetic measurements 7 8 6 5 PT TT 9

4 10 PT 11

3 13 12 2

14 PT 15

18

17 16 PLC

1

1 – Feed tank 12 – Balance 2, 5, 6, 9, 11, 15 – Valve 13 – Ceramic membrane 3 – Pump 16 – Programmable logic controler 4 – Rotametar 17 – Temperature controler 7, 10, 14 – Pressure transducer 18 – Computer 8 – Temperature transducer Ceramic membrane UF device CERAMIC MEMBRANES

• Cylindrical

• arranged within a wider tube with diametar around 25 mm • water is fed through the tubes, and the permeate is collected from the

Alumina is sintered to form Feed stream outside of the tube (within the wider a monolitic porous element carrier tube) Active layer • permeate flows inside-out and the retentate passes through the inside Support Permeate of the tube Feed stream channels within the popous alumina structure are lined with a selective membrane layer • not suitable for treating water with high suspended solids CERAMIC MEMBRANES M (PEG/PEO) ds [g mol-1] [nm] 1 300 0.899 2 600 1.341 3 950-1 050 1.801 4 1 305-1 595 2.100 5 2 050 2.725 Stokes radii of PEG and PEO molecules: 6 4 000 4.007 7 6 000 5.064 , 8 8 000 5.979 PEG: = 16.73 10 [cm] 9 10 000 6.800 −10 0 557 10 20 000 10.144 PEO: 푎 = 10.44� 10 � 𝑇𝑇 , [cm]. 11 35 000 14.010 −10 0 587 12 100 000 17.977 푎 � � 𝑇𝑇 13 300 000 34.261 14 600 000 51.464

100 RTO

80

60 1 kDa Membrane

[%] [%] 2 kDa R 40 500 kDa characterization

20

0 1 100 10,000 1,000,000 100,000,000

MWCO [g mol-1] 2 kDa 1,0

0,9 CERAMIC MEMBRANE ] - 1 kDa [ 0,8 FOULING STUDY Pn0 J 1,0 / Pn J 0,7 PEG 600 PEG 1 000 0,9 PEG 2 000 PEG 4 000 0,6 • the coefficients of the Hermia ] PEG 6 000 - [ 0,8 PEG 8 000 Pn0

J model of pore blocking models /

Pn 0,5 J PEG 300 0,7 PEG 600 0 20 40 60 80 100 120 were determined. PEG 1 000 t [min] PEG 1 450 0,6 PEG 2 050 • the blocking of the pores of PEG 4 000 500 kDa 0,5 the membrane material is best 0 20 40 60 80 100 120 t [min] described by the model of gel 1,0 layer formation, but at 1 kDa 0,8 and 500 kDa membranes there ] - [ is a moderate blocking of pores 0,6 Pn0 J / Pn

J due to the accumulation of

0,4 PEG 20 000 PEG 35 000 molecules within the pores of PEO 100 000 0,2 PEO 300 000 the membrane material PEO 600 000

0,0 0 20 40 60 80 100 120 t [min] TEXTILE WASTEWATER During textile dyeing process alkaline, acids, salts, whitening agents, solvent other auxiliary chemicals are added. Textile wastewater contains dyes, suspended solids, organic compounds, inorganic salts, often high temperature, turbidity and Wastewater treatment: alkalinity  Inside process unit (integrated)

 „end-of-pipe“

Integrated wastewater treatment, and reuse water and auxiliary chemicals is very important for textile industry 1.1

1.0

0.9 ] - [ P0 J / 0.8 P J

MERCERIZATION 1 kDa 0.7 2 kDa 500 kDa WASTEWATER 0.6

0.5 0 5 10 15 20 25 30 • During the mercerization process, textile was t [min] immersed in 25% sodium hydroxide solution and 1– 2% of wetting agent

• After mercerization, textile was rinsed with hot water and cold rinse water of 80°C and 18–20°C Parameter Wastewater 500 kDa 2 kDa 1 kDa pH 13.30 13.13 13.04 13.23 • NaOH is filtered and returned into the process -1 20 000 12 000 11 500 11 000 Alkalinity as CaCO3, mg L • 500 g NaOH for 1 kg cotton i 200 L wastewater per 75 100 48 400 48 700 43 900 batch Conductivity, µS cm-1 TSS, mg L-1 100.0 45.6 29.0 8.9 TDS, mg L-1 20 957 18 523 14 340 14 140 Turbidity, NTU 14.60 2.57 0.27 0.28 TOC, mg L-1 499.20 398.47 238.85 282.22 Colour, Pt-Co 205 81 52 4 1,1

1,0 Reactive dye wastewater REACTIVE DYE (NOVACRON reactive dyes-red and orange) ]

- 0,9 [ Pn0 J / 0,8 Pn

WASTEWATER J

0,7 CFV=1 m s-1 • the dyeing process is conducted in batch reactors CFV=2 m s-1 -1 of different capacity for 160 minutes 0,6 CFV=3 m s Wastewater 1 kDa permeate 0,5 0 20 40 60 80 100 120 • during the dyeing process, auxiliary chemicals, t [min] such as sodium chloride, sodium carbonate, sodium hydroxide, and oxidants are added Parameter Reactive dye wastewater 1 kDa

pH, - 11.46 9.26±0.01 • after completion of staining, the alkaline, coloured water with high concentration of colorants TSS, mg L-1 26.63 74.8±0.492 auxiliary chemicals is released into the sewer 16.61±0.785 Turbidity, NTU 1.45 system, and the thread is subsequently processed R=66.0%

0.29±0.04 TOC, mg L-1 C 585.8 • For 8 hours: 20 000 L wastewater R=61.2% 100.03±7.05 Conductivity, mS cm-1 76.3 R=70.54%

0.5694 Colour 1.7109 R=66.72% CERAMIC MEMBRANE CLEANING PROCEDURE

END OF ULTRAFILTRATION TEST

CIP 1 % NaOH 30 min T=50-60°C CIP 0.05 % NaOCl 30 min T=50-60°C 0.05 % NaOCl 60 min soaking T=50-60°C 1 % H2O2 60 min soaking T=50-60°C Deionized water rinse Deionized water rinse Deionized water rinse Deionized water rinse

Flux Flux NO Flux NO Flux recover NO recover recover recover NO y>90% y>90% y>90% y>90%

YES YES YES YES

NEW ULTRAFILTRATION TEST PHOTOCATALYTIC CERAMIC MEMBRANES • combination of photocatalysis and membrane separation technology is applied to the degradation of refractory antibiotic organic compounds in aqueous solutions

• synergy of both technologies makes a powerful system, with a membrane having the simultaneous task of supporting photocatalyst as well as acting as a selective barrier for species to be degraded

• photocatalysis could be adopted to improve the filtration performance of membranes as an in-situ method of fouling management

PHOTOCATALYTIC • preventing the accumulation of foulants on the membrane, the secondary waste disposal problem from using maintenance cleaning CERAMIC chemicals would be avoided • by immobilizing heterogeneous semiconductor photocatalysts such as titanium dioxide (TiO2) on the membrane surface, the separation function of membranes and the oxidative degradation ability of photocatalysts MEMBRANES could be combined into one unit to give a superior hybrid membrane material

• porous TiO2 layer is immobilized onto a porous substrate, such as Al2O3 and SiO2, where the TiO2 layer acts as an active skin layer, and the substrate layer acts as a mechanical support.

• preventing the accumulation of foulants on the membrane, the secondary waste disposal problem from using maintenance cleaning chemicals would be avoided PHOTOCATALYTIC CERAMIC MEMBRANES

• radiation energy provided by an energy source (UV lamp or sunlight), results in the creation of electron-hole pairs on the TiO2 photocatalyst coated membrane surface

• photo-generated hole then weakens the bond between titanium and the lattice oxygen atom, resulting in it being broken by water adsorbed to the membrane surface to form new Ti–OH bonds

• new hydroxyl groups on the membrane surface induce super-hydrophilicity, which prevents hydrophobic compounds from attaching to the membrane, thus keeping it free from foulants

• the chemical decomposition of organic molecules occurs concurrently with their physical separation PHOTOCATALYTIC CERAMIC MEMBRANES

One of the main challenges which is how to supply this light to the photocatalyst

• This becomes an even more significant challenge in turbid waters

• Since the chemical reaction takes some time, controlling the hydraulic residence time is essential PHOTOCATALYTIC CERAMIC MEMBRANES

Multiple function of membranes • Physical Separation

• Built-In Chemical Oxidation

• Water Detoxification

• Microbial Disinfection

• Antifouling Action Thank you!